Apparatus for performing fabricating operations on sheet material, and a combination of punch and die members for incorporation in such apparatus

ABSTRACT

A press apparatus for forming knock-outs in sheet metal panels to be subsequently formed into electrical enclosures, in which the apparatus comprises a plurality of pairs of punch and die members with the punch and die members of each pair thereof being complementary. Each of these punch and die members is removably mounted in the apparatus by means of a screw-threaded member which is centrally located relative to the associated punch or die member and is disposed through a locating spigot which is presented by the punch or die member and is located within a complementary recess provided in the apparatus, at least some of these punch and die members each being further removably mounted in the apparatus by means of an anti-rotation locking pin which is disposed partially within a recess in the associated punch or die member and partially within a bore provided in the apparatus. The dimensions of and spacing between the screw-thread member and the anti-rotation locking pin by which each of the appropriate punch and die members are removably mounted in the apparatus are the same, so that the pairs of punch and die members, which are of different dimensions, may be removed and re-mounted in the apparatus in different positions, the screw-threaded member and anti-rotation locking pin by which each appropriate punch and die member is removably mounted in the apparatus being wholly within the periphery of said member as viewed in the direction in which said punch or die member and the other member of the appropriate pair thereof are operatively movable towards and away from one another, so that the punch and die members of adjacent pairs thereof may be disposed in contacting relationship with one another.

APPARATUS FOR PERFORMING FABRICATING OPERATIONS ON SHEET MATERIAL, AND A COMBINATION OF PUNCH AND DIE MEMBERS FOR INCORPORATION IN SUCH APPARATUS [76] Inventor: Eugene Stephen Joseph, 120

Newport Ave., Scarborough, Ontario, Canada [22] Filed: Dec. 30, 1971 [21] Appl. No.: 213,967

[52] US. Cl 72/324, 72/327, 72/330, 72/331, 72/333, 83/695 [51] Int. Cl. ..B21d 43/28 [58] .Field of Search..... 72/324, 326, 327, 331, 333; 83/1, 695; 225/94, 96; 29/190 [56] References Cited UNITED STATES PATENTS 2,350,004 5/1944 Whistler et a1. 29/190 3,217,574 11/1965 Nauta et al, 83/108 3,580,122 5/1971 Powell 83/108 3,383,065 5/1968 Bergeron et a1. 242/568 3,413,880 12/1968 Foist 83/54 3,485,124 12/1969 Merchant 83/182 3,465,634 9/1969 Blais 83/695 3,137,188 6/1964 Domku' 83/124 3,119,292 l/1964 Schmid 83/124 3,111,053 11/1963 'Svensson 83/124 Primary Examiner-Charles W. Lanham Assistant Examiner-James R. Duzan Attorney, Agent, or FirmJ. A. Legris [57] ABSTRACT A press apparatus for forming knock-outs in sheet Jan. 29, 1974 a metal panels to be subsequently formed into electrical enclosures, in which the apparatus comprises a plurality of pairs of punch and die members with the punch and die members of each pair thereof being complementary. Each of these punch and die members is removably mounted in the apparatus by means of a screw-threaded member which is centrally located relative to the associated punch or die member and is disposed through a locating spigot which is presented by the punch or die member and is located within a complementary recess provided in the apparatus, at least some of these punch and die members each being further removably mounted in the apparatus by means of an anti-rotation locking pin which is disposed partially within a recess in the associated punch or die member and partially within a bore provided in the apparatus. The dimensions of and spacing between the screw-thread member and the anti-rotation locking pin by which each of the appropriate punch and die members are removably mounted in the apparatus are the same, so that the pairs of punch and die members, which are of different dimensions, may be removed and re-mounted in the apparatus in different positions, the screw-threaded member and anti-' rotation locking pin by which each appropriate punch and die member is removably mounted in the apparatus being wholly within the periphery of said member as viewed in the direction in which said punch or die member and the other member of the appropriate pui'r thereof are operatively movable towards and away from one another, so that the punch and die members of adjacent pairs thereof may be disposed in contacting relationship with one another.

24 Claims, 5 Drawing Figures PATENTEUJAN 29 1914 SHEEI 1 BF 3 or k Q aw on a 8 This invention is concerned with apparatus for performing fabricating operations on sheet material such trical enclosures, for upper and lower master shoes which in operation are mounted on the upper and lower platens of a press apparatus to be provided with as, for example, sheet metal panels. Thus, for example, I

the apparatus may operatively serve for the forming of knock-outs in sheet metal panels, the sheet metal panels subsequently being formed by appropriate bending into electrical enclosures such as, for example, electrical junction boxes or electrical switchboxes. Such knock-outs are conventionally provided in electrical enclosures to permit electrical wiring and the like to be disposed at the required positions through the walls of the electrical enclosures to the interiors thereof for, for example, connection to electrical terminals disposed within the enclosures, such knockouts each being in the form of a portion of a wall of the electrical enclosure which is severed from the surrounding portion of the wall except at one or more positions at which the central servered portion of the wall remains connected to the surrounding portion thereof through a connecting tab or tabs. The portion of the wall'which is so severed from the surrounding portion thereof is generally of circular form, and may be surrounded by one or more annular portions of the walls which are each likewise severed from the surrounding portion of the wall except at one or more positions at which they are each connected to the surrounding portion of the wall through a connecting tab or tabs. In this manner, when it is desired to dispose electrical wiring or the like through a wall of an electrical enclosureat the location of one of the knock-outs formed in the wall the central severed portion of the wall together, if required, with one or more of the surrounding severed annular portions are punched out with resultant breaking of the appropriate connecting tab or tabs thereby to provide an opening in the wall through which the wiring or the like is then disposed. As will be appreciated, the desired dimensions of the opening to be formed in the wall determines whether only the central severed portion of the wall or whether this portion together with one or more of the surrounding severed portions are punched out.

Prior to the punching out of the appropriate portion or portions of the knock-outs each of these severed portions is generally disposed in a plane which is staggered relative to the plane of the adjacent severed portion or of the surrounding portion of the wall of the enclosure, thereby to facilitate subsequent removal of the appropriate severed portion or portions, the central severed portion of the wall generally being disposed in a plane which is located inwardly relative to the associated enclosure of the plane containing the adjacent severed portion of the wall or the surrounding portion of the wall. As will be appreciated, of course, the planes in which the adjacent severed portions or the appropriate severed portion and the adjacent surrounding portion of the wall, are disposed are not, prior to the removal of. the appropriate severed portion or portions, spaced apart to such an extent that a gap is provided in the wall of the enclosure between these adjacent portions.

It has hitherto been the practice, in the forming of such knock-outs in sheet material, and more particularly in sheet metal panels intended to constitute elecone or more pairs of members, one of the members of each pair thereof being a punch member and the other member of each pair thereof being a die member, with the punch and die members of each pair of members being complementary and being so formed that during operation of the press a knock-out is formed in the sheet metal panel when the punch and die members of 7 each pair thereof are, on relative movement of these members towards one another, brought into mating juxtaposed relationship with the sheet metal disposed between the members. In such apparatus as hitherto used it has generally been the case that portions of the punch and die members of each pair thereof, which members may incorporate strippers for operatively urging the sheet material from the punch and die members of each pair of members when these members are operatively moved apart by the operation of the press apparatus after the knock-out has been formed in the sheet material, are disposed within the master'shoes, and generally within specially formed compartments which are provided in the master shoes and which are adapted to receive, for example, the above-mentioned strippers. Thus, the master shoes are particularly formed for punch and die members which are of a particular size and which are to be located at a particular position, the size and positioning of the punch and die members being, of course, dependent on the design of the particular electrical enclosure to be fabricated.

The result has been that such apparatus as hitherto used can economically be used only for a relatively large production run of an electrical enclosure of a particular design, since, of course, the cost of fabricating the upper and lower master shoes is relatively high and it is not feasible for the punch and die members readily to be removed and re-used in a different arrangement.

It is a primary object of the present invention to provide apparatus for performing fabricating operations on sheet material such as, for example, for forming knock-outs in sheet metal panels, inwhich the abovedescribed disadvantages of the apparatus as hitherto used are substantially overcome or obviated, and in which, more particularly, the punch and die members of each said pair thereof may readily be removed from the apparatus and reused in a different arrangement. It is to be understood, of course that the scope of the present invention is not restricted to apparatus in which the fabricating operations which may be performed by the apparatus on sheet material necessarily constitute the forming of knock-outs in sheet metal panels.

It is also a primary object of the present invention to provide a combination of punch and die members for incorporation in such apparatus.

It has hitherto been proposed to provide a press apparatus incorporating one or more pairs of punch and die members which may be removed from the apparatus and reused in different arrangements and in which, therefore, the above-described disadvantages of the hitherto used form of apparatus is substantially overcome, attention in this connection being particularly directed to U.S. Pat. No. 2,350,004 which issued on May 30, 1944 to L.V. Whistler et al and which is the most relevant prior art of which the applicant isaware. Thus, it will be noted that with particular reference to, for example, FIG. 1 of the drawing of this patent to Whistler et al. there is therein disclosed apparatus including a punch-holder and a die-holder on which a punch-member and a die-member, respectively, are removably mounted by means of retainer-elements which, as is most clearly shown in FIG. 3, are secured to the punch-holder and the die-holder by means of screws. Whistler et al also disclose the use of dowel pins each of which is disposed within one of the retainerelements and the adjacent punch-holder or die-holder.

It will be noted, however, that in the apparatus disclosed by Whistler et al it would clearly be necessary with punch members and die members of different diameters to provide retainer-elements of corresponding different diameters, and in addition for punch members and die members of different diameters the spacing between the screws and the dowel pins would likewise be correspondingly different. Thus, it is a disadvantage of the apparatus disclosed by Whistler et al that it is clearly not possible for punch members and die members of different dimensions to be removably mounted at the same locations on the punch-holder and the dieholder by means of the same retainer-elements, and screws together with dowel pins which are located in the punch-holder and the die-holder at the same posi tions.

It is accordingly also an object of one aspect of the present invention to provide apparatus for performing fabricating operations on sheet material in which these disadvantages of the apparatus disclosed by Whistler et al are substantially overcome, and to provide a combination of at least two pairs of punch and die members for incorporation in such apparatus.

It is a further disadvantage of the apparatus disclosed by Whistler et al. that the retainer-elements together with the screws and the dowel pins by means of which each punch member and die member are removably mounted on the punch-holder or the die-holder, are disposed outside the peripheries of the punch member and the die member as viewed in the direction in which these punch and die members are relatively movable towards and away from one another, since it is thereby impossible for adjacent pairs of the punch and die members to be disposed in substantially contacting relationship. It may frequently be desirable for adjacent pairs of the punch and die members to be disposed in substantially contacting relationship, and this has apparently been appreciated by Whistler et al since they have disclosed a modified form of the apparatus which is shown in FIGS. 21 and 22 of the drawings of the patent and in which it will be noted that the adjacent pairs of punch and die members may be disposed in closer relationship although it is still not possible even with thismodified apparatus of Whistler et a] for the adjacent pairs of punch and die members to be disposed in contacting relationship.

It is accordingly an object of a further aspect of the present invention to provide apparatus for performing fabricating operations on sheet material in which this latter disadvantage of the apparatus disclosed by Whistler et al is substantially overcome, and in which more particularly adjacent pairs of the punch and die members may, if desired, be disposed in substantially contacting relationship. It is also an object of this aspect of the present invention to provide a combination comprising at least one pair of punch and die members for incorporation in such apparatus.

In order that the present invention may be more clearly understood and more readily carried into effect the same will now, by way of example, be more fully described with reference to the accompanying drawings in which FIG. 1 is a vertically sectioned view of a part of an apparatus according to a preferred embodiment of the present invention for performing fabricating operations on sheet material, the view being taken substantially on the line 11 of FIG. 2;

FIG. 2 is a plan view of the part of the apparatus shown in FIG. 1, this view being taken substantially on the line 22 in FIG. I with the sheet metal panel disposed within the apparatus shown in chain-dotted lines;

FIG. 3 is a plan view substantially corresponding to FIG. 2 but showing only the sheet metal panel after the performing thereon by the apparatus of the appropriate fabricating operations;

FIG. 4 is a sectioned view of the portion of the sheet metal panel shown in FIG. 3 substantially on the line 44 in FIG. 3; and

FIG. 5 is a vertically sectioned view substantially on the line 55 in FIG. 2.

Referring to the drawings, and particularly to FIG. 1 thereof, 10 denotes generally each of a plurality of pairs of members, one of the members of each pair 10 thereof being a punch member and the other member of each pair 10 thereof being a die member. The punch members of the pairs 10 of members are denoted respectively by the reference numerals 11, 12, 13, 14 and 15, and the die members of the pairs 10 thereof are denoted respectively by the reference numerals 16, 17, 18, 19 and 20.

The punch member 12 of the appropriate pair 10 of members comprises a centrally disposed, approximately cylindrical rigid portion 21 which is disposed within an annular rigid portion 22, the portion 21 presenting an annular shoulder 23 with which an annular flange 24, presented by the portion 22 is in abutting engagement. The portion 22 is also provided with an inner annular recess within which an annular body 25 is disposed, and with an outer annular recess within which an annular body 26 is disposed.

A transverse bore 27 is provided in the portion 22, this bore 27 being in alignment with a slot 28 provided in the portion 21 with a locking pin 29 operatively disposed partially within the bore 27 and partially within the slot 28 thereby substantially to prevent relative rotation between the portions 21 and 22.

The die member 17 of the pair 10 of members which includes the punch member 12 comprises a centrally disposed, approximately cylindrical rigid portion 30 which is disposed within an annular rigid portion 31, the portion 30 presenting an annular shoulder 32 with which an annular flange 33 presented by the portion 31 is in abutting engagement. The portion 30 is provided with a centrally disposed recess within which a body 34 which is secured to the portion 30 by means of a screwthreaded member 35 is located, the portion 30 also being provided with an annular recess within which an annular body 36 is disposed.

As shown in FIG. 1, the dimensions of the portion 21 of the punch member 12 are such that this portion 21 is a close sliding fit within the recess in the portion 30 of the die member 17 within which the body 34 is disposed, the dimensions of the annular part of the portion 22 of the punch member 12 between the recesses in which the bodies 25 and 26 are disposed likewise being such that this annular part of the portion 22 is a close sliding fit within the recess in the portion 30 of the die member 17 within which the body 36 is disposed. Thus, since the bodies 25, 26, 34 and 36 are each constituted by a stiff, but resiliently deformable plastics material such as, for example, polyurethane, the portion 21 together with the above-mentioned annular part of the portion 22 of the punch member 12 may, with resultant resilient deformation of the bodies 25, 26, 34 and 36, operatively enter into the appropriate recesses in the portion 30 of the die member 17 as shown in FIG. 1, when the punch and die members 12 and 17 are relatively moved towards one another so that the punch and die members 12 and 17 are therefore complementary. Such relative movement of the punch and die members 12 and 17 towards one another results in sheet material 37 which has been disposed between the punch and die members 12 and 17 being formed with three concentric lines of severance 38 which are more clearly shown in FIGS. 3 and 4 and the outer two of which are each continuous except at two diemetrically opposed locations at which the adjacent portions of the sheet material 37 separated by the lines of severance 38 remain interconnected through connecting tabs 39. The inner line of severance 38 is continuous except at a single location at which the adjacent portions of the sheet material 37 separated by the appropriate line of severance 38 remain interconnected through a further connecting tab 39.

With particular reference to FIG. 1, these connecting tabs 39-result from the provision of notches 40 in the portion 21 and the above-mentioned annular part of the portion 22 of the punch member 12 and in the portion 31 of the die member 17.

Thus, the pair of members comprising the punch member 12 and the die member 17 operatively perform on the sheet material 37, which may be a sheet metal panel, a fabricating operation, which results in the formation of a knock-out which is in fact in the form of a triple knock-out in that it comprises three concentric lines of severance 38.

The punch and die members 11 and 16, respectively, are substantially identical tothe punch and die members 12 and 17, respectively, except that, as will be noted from the drawings, the diameters of the various elements of the punch and die members 11 and 16 are somewhat less than the diameters of the corresponding elements of the punch and die members 12 and 17 with the result that, as shown in FIGS. 3 and 4, the diameters of the three lines of severance 38 which are operatively formed in the sheet material 37 by the pair 10 of members comprising the punch member 11 and the die member 16 are somewhat less than the diameters of the three lines of severance 38 operatively formed in the sheet material 37 by the pairs 10 of members comprising the punch member 12 and the die member 17. For convenience, the same reference numerals have been used in the drawings to denote the appropriate elements of the punch member 11 and the die member 16 as have been used to denote the corresponding elements of the punch member 12 and the die member 17, respectively.

With reference to the pair 10 of members comprising the punch member 13 and the die member 18, it will be noted from FIG. 1 that except as noted hereinafter the punch member 13 is substantially identical to the die member 17, and except as noted hereinafter the die member 18 is substantially identical to the punch member 12. For convenience therefore the same reference numerals have been used to denote the various elements of the punch member and the die member 18 as have been used to denote the corresponding elements of the die member 17 and the punch member 12, respectively. I

The punch member 13 differs from the die member 17 in that in the punch member 13 there is no element corresponding to the portion 31 of the die member 17, so that of course the portion 30 of the punch member 13 does not present an annular'shoulder 32. The die member 18 differs from the punch member 12 in that the portion 22 of the die member 18 is not provided with an annular recess within which an annular body 26 is disposed, and in that the recess within which the annular body 25 is disposed is provided in the portion 21 of the die member 18 rather than in the portion 22 thereof.

Thus, the pair 10 of members comprising the punch member 13 and the die member 18 operatively forms in the sheet material 37 a knock-out which is in the form of a double knock-out in that it comprises merely two concentric lines of severance 38, as is shown particularly in FIGS. 3 and 4 of the drawings. Particularly from FIG. 3 it will also be noted that in the knock-out operatively formed by the punch and die members 13 and 18 the adjacent portions of the sheet material 37 which are separated by each of the lines of severance 38 remain interconnected only through a single connecting tab 39.

The punch member 14 of the appropriate pair 10 of members comprises an approximately cylindrical, rigid portion 74 on the lower end of which is operatively mounted a body 41 of stiff but resiliently deformable plastics material such as, for example, polyurethane, a punch pin 42 being mounted through a bore provided in the body 41 and within an elongated recess provided in the portion 74. The upper end portion of the pin 42 is provided with an snnular groove 43 within which is disposed the inner end of a screw-threaded member 44 which is screw-threadedly mounted within a transverse bore provided in the portion 74 of the punch member 14. The member 44 thus serves substantially to prevent inadvertent removal of the pin 42 from the punch member 14.

The die member 29 with which the punch member 13 is associated comprises an approximately cylindrical, rigid portion 45 which is provided with a passage 46 within which the lower end portion of the punch pin 42 may enter as a close, sliding fit so that the punch and die members 14 and 19 are thus complementary, the passage 46 communciating with an inclined discharge opening 47 through which a portion of the sheet material 37, which is operatively severed from the remainder of the sheet material 37 as the lower end portion of the punch pin 42 enters the passage 46 on relative movement of the punch member 14 and the die member 19 towards one another is discharged from the die member 19.

Referring to the pair 10 of members comprising the punch member 15 and the die member 20, the punch member 15 comprises a rigid portion 48 which'is ccntrally provided with a bore within which an approximately cylindrical, rigid portion 49 is disposed, this portion 49 presenting at the upper end thereof a projecting part 50 which may be of approximately rectangular form in cross-section. The portion 49 has at the lower end thereof an enlarged head 72, a transverse slot being provided in the lower face of the portion 48 with a part of one of the sides of this slot being constituted when the portion 59 is in the appropriate angular orientation by a flat provided on the head 72 which is otherwise of circular form.

A key 73 is disposed as a press fit within the slot when the portion 49 is in said angular orientation thereby to maintain the portion 49 in this orientation.

The die member 20 is provided with a recess within which a body 51 of stiff, but resiliently deformable plastics material such as, for example, polyurethane is disposed, the part 50 of the portion 49 of the punch member being a close, sliding flat relative to three of the sides of the recess within which the body 51 is disposed, but being in spaced relationship relative to the fourth side of this recess, whereby on operative movement of the part 50 into the recess within which the body 51 is disposed caused by relative movement of the punch member 15 and the die member towards one another with the sheet material 37 disposed the rebetween a projecting hook 52 as shown in FIGS. 3 and 4 is operatively formed in the sheet material 37.

With particular reference to FIG. 2, the reference numeral 53 denotes each of a plurality of punch members of pairs of punch and die members for forming triple knock-outs, the punch members 53 being substantially identical to one another and to the punch member 12 as hereinbefore described with particular reference to FIG. 1, except that as required the dimensions of the various elements of these punch members 53 may differ from one another and from the dimensions of the corresponding elements of the punch member 12. The same reference numerals have been used to denote the appropriate elements of each of these punch members 53 as have been used to denote the corresponding elements of the punch member 12. Likewise, in FIG. 2 the reference numeral 54 denotes each of a plurality of die members of pairs of punch and die members for forming double knock-outs, the die members 54 each being substantially identical to one another and to the die member 18 hereinbefore described with particular reference to FIG. 1. The appropriate elements of these die members 54 are again denoted by the same reference numerals as have been used to denote the corresponding elements of the die member 18. The reference numeral 55 denotes each of a plurality of die members of pairs of punch and die members for forming knockouts each of which is in the form of a single knock-out in that it comprises a single line of severance 38 in the sheet material 37. Although such a pair of punch and die members for forming a single knock-out is not specifically shown in FIG. 1 it will, of course, be appreciated that in such a pair of punch and die members the punch member could substantially correspond to the punch member 13 with the omission of the body 36 and the die member could substantially correspond to the die member 18 with the omission of the portion 22. The reference numeral 56 denotes each of a plurality of die members of pairs of punch and die members, the die members 56 being substantially identical to one another end to the die member 19, except that as required the dimensions of the various elements of each of the die members 56 may differ from one another and from the dimensions of the corresponding elements of the die member 19. The appropriate elements of the die members 56 have been denoted by the same reference numerals as the corresponding elements of the die member 19.

With particular reference again to FIG. 1, the various pairs 10 of punch and die members are adapted to be removably mounted in apparatus, such as a press apparatus, for performing fabricating operations on sheet material, the apparatus incorporating an upper platen 57 and a lower platen 58. These platens 57 and 58, only portions of which are shown in FIG. 1, are operatively relatively urged towards and away from one another by power means such as, for example, mechanical power means (not shown) as is conventional in a press apparatus. Mounted on the lower face of the upper platen 57 by appropriate mounting means (not shown) is an upper master shoe 59, and mounted on the upper face of the lower platen 58 by appropriate mounting means (not shown) is a lower master shoe 60. An upper template 61 is mounted on the lower face of the upper master shoe 59 and a lower template 62 is mounted on the upper face of the lower master shoe 60, these templates 61 and 62 being each so mounted by means of a clamping bar arrangement which comprises a plurality of clamping bars including the clamping bar 63 shown in FIG. 1. The clamping bars 63 are each of substantially L-shape in cross-section and comprise a first limb which overlies the appropriate template 61 or 62 and a second limb which is mounted on the appropriate master shoe S9 or and which is operatively rigidly secured thereto by a plurality of spaced, screwthreaded bolts 64, a plurality of screw-threaded locating members constituted by screw-threaded bolts 65 being disposed through the template 61 or 62 and being screw-threadedly engaged with the appropriate master shoe 59 or 60 thereby accurately to position the appropriate template 61 or 62 on the master shoe 59 or 60, respectively, prior to the clamping of the template 61 or 62 to the master shoe 59 or 60, respectively, by means of the clamping bar arrangement comprising the clamping bars 63.

Operative movement of the platens 57 and 58 relatively towards one another with the pairs 10 of punch and die members removably mounted in the apparatus results in said members of each pair 10 thereof being brought into mating juxtaposed relationship so that with the sheet material 37 such as for example, a sheet metal panel disposed between the punch and die makers of each pair 10 thereof a fabricating operation is performed thereon, this operation in the case of, for example, the pairs 10 of members comprising the punch members 111, 12 and 13 and the die members 16, 17 and 18 resulting in the forming of knock-outs in the sheet material, in the case of, for example, the pair 10 of members comprising the punch member 14 and the die member 19 resulting in a hole denoted by the reference numeral 71 in FIGS. 3 and 4 being formed in the sheet material 37, and in the case of, for example, the pair of members comprising the punch member 15 and the die member 20 resulting in the forming of the projecting hook 52 in the sheet material 37. During these fabricating operations the bodies 25, 26, 34, 36, 41 and 51 of, for example, polyurethane are of course resiliently deformed so that during the subsequent movement of the platens 57 and 58 relatively away from one another the resilient stressing in these bodies 25, 26, 34, 36, 41 and 51 is relieved with resultant urging of the sheet material 37 from the appropriate punch and die members of these pairs of members. These bodies 25, 26, 34, 36, 41 and 51 thus serve as stripper arrangements.

Each of the punch members 11, 12, 13, 14 and and each of the die members 16, 17, 18, 19 and is removably mounted in the apparatus by mounting means which in the preferred embodiment of the invention illustrated in the drawings comprises a screwthreaded member in the form of a screw-threaded bolt 66 which serves removably to mount the associated punch or die member in the apparatus and more particularly to secure the associated punch or die member to the appropriate template 61 or 62, these bolts 66 except in the case of the punch member 15 and the die member 20 being disposed through the appropriate template 61 or 62 and being screw-threadedly engaged with the appropriate punch or die member'at a position substantially centrally thereof. Each bolt 66 is disposed through a locating spigot 67 which is presented by the appropriate punch or die member and which is operatively disposed within a complementary recess provided in the apparatus and more particularly in the appropriate template 61 or 62.

With particular reference to the punch member 15 and the die member 20, each of these members is provided with a pair of the screw-threaded bolts 66 which are disposed on opposite sides of the centre of the punch member 15 or the die member 20 and each of which is disposed in a recess 68 in the member and passes through the member for screw-threaded engagement'in the apparatus and more particularly in the appropriate template 61 or 62.

With particular reference to the punch members 11, 12, 13 and 14 and the die members 16, 17, 18 and 19 it will be noted that the mounting means comprising the screw-threaded bolts 66 are each disposed wholly within the periphery of the appropriate punch or die member, as viewed in the direction in which this member and the other member which together with said member constitute a pair 10 of the members are relatively movable. Thus, in this manner, it is possible for adjacent pairs 10 of punch and die members to be disposed in close relationship, or even to be disposed in contacting relationship, as shown in, for example, FIG. 1 in which the pair 10 of members comprising the punch member 11 and the die member 16 are disposed in contacting relationship with the pair 10 of members comprising the punch member 12 and the die member 17.

It is to be emphasized, that in relation to this aspect of the present invention there need be only one, although there are preferably at least two, pairs 10 of punch and die members in each of which the mounting means by which the member is operatively removably mounted in the apparatus is disposed wholly within the periphery of the member as viewed in the abovementioned direction, since even in an apparatus incorporating a plurality of pairs of punch and die members only one of which pairs of members is of a form according to this aspect of the present invention it will of course still be possible for this pair 10 of members according to this aspect of the present invention to be disposed more closely to the adjacent pair of punch and die members than would otherwise be the case. It will be noted that in each of the pairs 10 of punch and die members the punch member and the die member is self-contained in that it may readily be removed as a unit from the apparatus and subsequently, when required, replaced as a unit in the apparatus, although, of course, if any damage is sustained by an individual element or elements in one of the punch or die members the member can be dismantled, the damaged element replaced and the member reassembled so that it is not necessary to discard the entire punch or die member in which the damaged element is incorporated.

I With particular reference to the pairs 10 of members comprising the punch members 11, 12, 13 and 14 and the die members 16, 17, 18 and 19, the dimensions of the members of each of these pairs 10 of members may, as hereinbefore indicated, tbe different. However, the dimensions of the mounting means comprising the screw-threaded bolts 66 for removably mounting the members of these pairs 10 of members in the apparatus are the same, so that, as required, the positions at which these pairs 10 of members are removably mounted in the apparatus may be altered by, for example, removing the pair 10 of members comprising the punch member 12 and the die member 17 and removing the pair 10 of members comprising the punch member 13 and the die member 18 and re-mounting these pairs 10 of members in the apparatus with the pair 10 of members comprising the punch member 13 and the die member 18 mounted at the position in which the pair 10 of members comprising the punch member 12 and the die member 17 are shown in FIG. 1, and with the pair 10 of members comprising the punch member 12 and the die member 17 mounted at the position in which the pair 10 of members comprising the punch member 13 and the die member 18 are shown in FIG. 1. In this manner, the various pairs 10 of members may, as required, be removed and either these pairs 10 of members may then be re-mounted in the apparatus at different positions or other pairs 10 of members according to the invention may be mounted in the apparatus in order to provide a different arrangement.

It is to be emphasized that, in relation to this aspect of the invention, it is only necessary that there be at least two pairs 10 of members with'the dimensions of the punch and die members of one of the pairs 10 thereof being different from the dimensions of the punch and die members of the other of the pairs 10 thereof, the dimensions of the mounting means comprising the bolt 66 by which one of the punch and die members of one of the pairs 10 of members is removably mounted in the apparatus being the same as the dimensions of the mounting means comprising the bolt 66 by which one of the punch and die members of the other of the pairs 10 thereof is removably mounted in the apparatus, and the dimensions of the mounting means comprising the bolt 66 by which the other of the punch and die members of said one of the pairs 10 thereof is removably mounted in the apparatus being the same as the dimensions of the mounting means comprising the bolt 66 by which the other of the punch and die members of said other of the pairs 10 thereof is removably mounted in the apparatus.

With particular reference to the pairs 10 of punch and die members comprising the punch members 11, 12 and 13 and the die members 16, 17 and 18, it will be noted from FIG. 1 that the mounting means for removably mounting each of these members in the apparatus comprises a plurality of spaced mounting members, these spaced mounting members in the preferred embodiment shown in the drawings being constituted by the above-mentioned screw-threaded bolt 66 and an anti-rotation locking pin 69 which is disposed partially within a recess provided in the portion 21 of the punch member 11 or 12 or the portion 30 of the punch member 13, or partially within a recess provided in the por tion 30 of the die members 16 or 17, or the portion 21 of the die member 18, and partially within a recess provided in the apparatus, and more particularly a bore 70 provided in the appropriate template 61 or 62.

The dimensions of the anti-rotation locking pin 69 and the relative spacing between this member 69 and the bolt 66 by which each of the above-mentioned punch and die members is removably mounted in the apparatus are also the same, or at least the dimensions of the anti-rotation locking pin 69 and the spacing between this member 69 and the bolt 66 by which said one of the punch and die members of said one of the pairs of members is removably mounted in the apparatus are the same as the dimensions of the pin 69 and the spacing between this member 69 and the bolt 66 by which said one of the punch and die members of said other of the pairs 10 of members is removably mounted in the apparatus, and the dimensions of the pin 69 and the spacing between this member 69 and the bolt 66 by which said other of the punch and die members of said one of the pairs 10 of members is removably mounted in the apparatus are the same as the dimensions of the pin 69 and the spacing between this member 69 and the bolt 66 by which said other of the punch and die members of said other of said pairs of members is removably mounted in the apparatus. Thus, the position of these pairs 10 of punch and die members in the apparatus may be altered, or some of these pairs 10 of punch and die members may be removed from the apparatus and other pairs 10 of punch and die members according to the invention substituted therefor.

What I claim as my invention is:

1. Apparatus according to claim 6, wherein said at least one pair of members comprises at least two pairs of said members, the dimensions of the punch and die members of one of said pairs thereof being different from the dimensions of the punch and die members of the other of said pairs thereof, with the dimensions of the mounting means by which one of the punch and die members of one of said pairs thereof is removably mounted in the apparatus being the same as the dimensions of the mounting means by which one of the punch and die members of the other of said pairs thereof is removably mounted in the apparatus, and with the dimensions of the mounting means by which the other of the punch and die members of said one of said pairs thereof is removably mounted in the apparatus being the same as the dimensions of the mounting means by which the other of the punch and die members of said other of said pairs thereof is removably mounted in the apparatus.

2. Apparatus according to claim 1, wherein the mounting means by which each of said punch and die members is removably mounted in the apparatus comprises a plurality of spaced mounting members, the spacing between the mounting members by which said one of the punch and die members of said one of the pairs thereof is removably mounted in the apparatus being the same as the spacing between the mounting members by which said one of the punch and die members of said other of the pairs thereof is removably mounted in the apparatus, and the spacing between the mounting members by which said other of the punch and die members of said one of the pairs thereof is removably mounted in the apparatus being the same as the spacing between the mounting members by which said other of the punch and die members of said other of the pairs thereof is removably mounted in the apparatus.

3. Apparatus according to claim 1, wherein each mounting means is substantially centrally disposed relative to the punch or die member which is removably mounted by said mounting means in the apparatus.

4. Apparatus for performing fabricating operations on sheet material, the apparatus comprising at least two pairs of members, one of the members of each said pair thereof being a punch member and the other member of each said pair thereof being a die member with the punch and die members of each pair of said members being complementary, and the members of each said pair thereof being relatively movable towards and away from one another, so that said members, on said relative movement thereof towards one another, are brought into mating juxtaposed relationship for performing a fabricating operation or operations on sheet material disposed between said members, wherein the dimensions of the punch and die members of one of said pairs thereof are different from the dimensions of the punch and die members of the other of said pairs thereof, each of the punch and die members being removably mounted in the apparatus by mounting means which comprises a plurality of spaced mounting members, the dimensions of and spacing between the mounting members by which one of the punch and die members of one of the pairs thereof is removably mounted in the apparatus being the same as the dimensions of and spacing between the mounting members by which one of the punch and die members of the other of the pairs thereof is removably mounted in the apparatus, the dimensions of and spacing between the mounting members by which the other of the punch and die members of said one of the pairs thereof is removably mounted in the apparatus being the same as the dimensions of and spacing between the mounting members by which the other of the punch and die members of said other of the pairs thereof is removably mounted in the apparatus, and the spaced mounting members by which at least one of said punch and die members is removably mounted in the apparatus comprising a screw-threaded member which is engaged in said punch or die member and in the apparatus, and an anti-rotation locking pin which is spaced from the screw-threaded member and which is engaged in recesses provided in said punch or die member and in the apparatus.

5. Apparatus according to claim 4, wherein said at least one of said punch and die members and the other member which is complementary thereto are formed for the forming of knock-outs in sheet material.

6. Apparatus for performing fabricating operations on sheet material, the apparatus comprising at least one pair of members, one of the members of said pair thereof being a punch member and the other member of said thereof being a die member with the punch and die members of said pair of members being complementary, and with the members of said pair thereof being relatively movable towards and away from one another, so that said members, on said relative movement thereof towards one another, are brought into mating juxtaposed relationship for performing a fabricating operation or operations on sheet material disposed between said members, wherein each of said punch and die members is self-contained and is as a unit removably mounted in the apparatus by mounting means which is disposed wholly within the periphery of said member as viewed in the direction in which said member and the other member which together with said member constitute said pair of members are relatively movable.

7. Apparatus according to claim 6, wherein said at least one pair of members comprises at least two pairs of members, one of the members of each said pair thereof being a punch member and the other member of each said pair thereof being a die member with the punch and die members of each pair of said members being complementary, and with the members of each said pair thereof being relatively movable towards and away from one another, so that said members, on said relative movement thereof towards one another, are brought into mating juxtaposed relationship for performing a fabricating operation or operations on sheet material disposed between said members, wherein each of said punch and die members is self-contained and is a unit removably mounted in the apparatus by mounting means which is disposed wholly within the periphery of said member as viewed in the direction in which said member and the other member which together with said member constitutes one of said pairs of members are relatively movable.

8. Apparatus according to claim 6, wherein the mounting means presented by at least one of the punch and die members of said pair thereof comprises a screw-threaded member which is engaged in said punch or die member and in the apparatus.

9. Apparatus according to claim 6, wherein the mounting means presented by at least one of the punch and die members of said pair thereof comprises a single screw-threaded member which is engaged in said punch or die member and in the apparatus, a locating spigot in which the screw-threaded member is disposed being presented by said punch or die member and being in engagement within a complementary recess provided in the apparatus.

10. Apparatus according to claim 6, further comprising at least one template, one of the punch and die members of said pair thereof being removably mounted on the template, and the template being removably mounted in the apparatus.

11. Apparatus according to claim 6, further comprising at least one template removably mounted in the apparatus, the mounting means presented by at least one of the punch and die members of said pair thereof comprising a single screw-threaded member which is engaged in said punch or die member and in the template, and a locating spigot in which the screw-threaded member is disposed being presented by said punch or die member and being in engagement within a complementary recess provided in the template.

12. Apparatus according to claim 10, wherein screwthreaded locating members are disposed through the template and engaged with the apparatus thereby to ensure accurate positioning of the template in the appara- 13. Apparatus according to claim 10, wherein a clamping bar arrangement which is mounted in the apparatus is disposed in secure engagement with the template thereby to provide said removable mounting of the template in the apparatus.

14. A combination according to claim 13, wherein said at least one pair of members comprises at least two pairs of said members, the dimensions of the punch and die members of one of said pairs thereof being different from the dimensions of the punch and die members of the other of said pairs thereof, the dimensions of the mounting means presented by one of the punch and die members of one of said pairs thereof being the same as the dimensions of the mounting means presented by one of the punch and die members of the other of said pairs thereof, and the dimensions of the mounting means presented by the other of the punch and die members of said one of pairs thereof being the same as the dimensions of the mounting means presented by the other of the punch and die members of said other of said pairs thereof.

15. A combination according to claim 14, wherein the mounting means by which each of said punch and die members is removably mountable in the apparatus comprises a plurality of spaced mounting members, the spacing between the mounting members presented by said one of the punch and die members of said one of the pairs thereof being the same as the spacing between the mounting members presented by said one of the punch and die members of said other of the pairs thereof, and the spacing between the mounting members presented by said other of the punch and die members of said one of the pairs thereof being the same as the spacing between the mounting members presented by said other of the punch and die members of said other of the pairs thereof.

16. In combination, at least two pairs of members, one of the members of each said pair thereof being a punch member and the other member of each said pair thereof being a die member with the punch and die members of each said pair of said members being complementary, the dimensions of the punch and die members of one of said pairs thereof being different from the dimensions of the punch and die members of the other of said pairs thereof, each of said punch and die members presenting mounting means by which the member is removably mountable in apparatus for performing fabricating operations on sheet material, for relative movement of the punch and die members of each said pair thereof towards and away from one another, so that said punch and die members of each said pair thereof, on relative movement thereof towards one another, are brought into mating juxtaposed relationship for performing a fabricating operation or operations on sheet material disposed between said punch and die members, each mounting means being substantially centrally disposed relative to the punch or die member from which said mounting means is presented, the dimensions of the mounting means presented by one of the punch and die members of one of said pairs thereof being the same as the dimensions of the mounting means presented by one of the punch and die members of the other of said pairs thereof, and the dimen-' sions of the mounting means presented by the other of the punch and die members of said one of said pairs thereof being the same as the dimensions of the mounting means presented by the other of the punch and die members of said other of said pairs thereof.

17. In combination, at least two pairs of members, one of the members of each said pair thereof being a punch member and the other member of each said pair thereof being a die member with the punch and die members of each said pair of said members being complementary, the dimensions of the punch and die members of one of said pairs thereof being different from the dimensions of the punch and die members of the other of said pairs thereof, each of said punch and die members presenting mounting means by which the member is removably mountable in apparatus for performing fabricating operations on sheet material, for relative movement of the punch and die members of each said pair thereof towards and away from one another, so that said punch and die members of each said pair thereof, on relative movement thereof towards one another, are brought into mating juxtaposed relationship for performing a fabricating operation or operations on sheet material disposed between said punch and die members, the mounting means by which each of said punch and die members is removably mountable in the apparatus comprising a plurality of spaced mounting members, the dimensions of and spacing between the mounting members presented by one of the punch and die members of one of the pairs thereof being the same as the dimensions of and spacing between the mounting members presented by one of the punch and die members of the other of the pairs thereof, the dimensions of and spacing between the mounting members presented by the other of the punch and die members of said one of the pairs thereof being the same as the dimensions of and spacing between the mounting members presented by the other of the punch and die members of said other of the pairs thereof, and the spaced mounting members by which at least one of said punch and die members is removably mountable in the apparatus comprising a screw-threaded member which is engageable in said punch or die member and in the apparatus, and an anti-rotation locking pin which is engageable in spaced relationship to the screwthreaded member in a recess provided in said punch or die member and in a recess in the apparatus.

18. A combination according to claim 17, wherein said at least one of said punch and die members and the other member which is complementary thereto are formed for the forming of knock-outs in sheet material.

19. In combination, at least one pair of members, one of the members of said pair thereof being a punch member and the other member of said pair thereof being a die member with the punch and die members of said pair of members being complementary, each of said punch and die members being self-contained and presenting mounting means by which said member is as a unit removably mountable in apparatus for performing fabricating operations on sheet material, for relative movement of the members of said pair thereof towards and away from one another, so that said members of said pair thereof, on relative movement thereof towards one another, are brought into mating juxtaposed relationship for performing a fabricating operation or operations on sheet material disposed between said members, the mounting means presented by each of said punch and die members being disposed wholly within the periphery of said member as viewed in the direction in which said member and the other member which together with said member constitutes said pair of members are relatively movable when removably mounted in the apparatus.

20. A combination according to claim 19, wherein said at least one pair of members comprises at least two pairs of members, one of the members of each said pair thereof being a punch member and the other member of each said pair thereof being a die member with the punch and die members of each said pair of members being complementary, each of said punch and die members being self-contained and presenting mounting means by which said member is as a unit removably mountable in apparatus for performing fabricating operations on sheet material, for relative movement of the members of each said pair thereof towards and away from one another, so that said members of each said pair thereof, on relative movement thereof towards one another, are brought into mating juxtaposed relationship for performing a fabricating operation or operations on sheet material disposed between said members, the mounting means presented by each of said punch and die members being disposed wholly within the periphery of said member as viewed in the direction in which said member and the other member which together with said member constitutes one of said pairs of members are relatively movable when removably mounted in the apparatus.

21. A combination according to claim 19, wherein the mounting means presented by at least one of the punch and die members of said pair thereof comprises a screw-threaded member which is engageable in said punch or die member and in the apparatus.

22. A combination according to claim 19, wherein the mounting means presented by at least one of the punch and die members of said pair thereof comprises a screw-threaded member which is engageable in said punch or die member and in the apparatus, a locating spigot in which the screw-threaded member is disposable being presented by said punch or die member and being engageable within a complementary recess provided in the apparatus.

23. A combination according to claim 19, wherein at least one of the punch and die members of said pair thereof incorporates a stripper arrangement constituted by a stiff but resiliently deformable plastics material.

24. Apparatus for the forming of knock-outs in sheet material, the apparatus comprising at least two pairs of members, one of the members of each said pair thereof being a punch member and the other member of each said pair thereof being a die member with the punch and die members of each said pair of said members being complementary, and the members of each said pair thereof being relatively movable towards and away from one another, so that said members, on said relative movement thereof towards one another, are brought into mating juxtaposed relationship for the forming, by the complementary punch and die members, of knock-outs in a sheet of formable material disposed between said members, wherein the dimensions of the punch and die members of one of said pairs thereof differ from the dimensions of the punch and die members of the other of said pairs thereof, each of said punch and die members being self-contained and being as a unit removably mounted in the apparatus by a plurality of spaced mounting members which comprise a screw-threaded member engaged in said punch or die member and in a template removably mounted in the apparatus, and an anti-rotation locking pin which is spaced from the screw-threaded member and which is her as viewed in the direction in which said punch or die member and the other member which together with said punch or die member constitutes one of said pairs of members are relatively movable, and the dimensions of-and spacing between the mounting members by which said punch and die members are removably mounted in the apparatus being substantially equal.

I 4 0 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent: No.3,788,-ll8 Dated January 29, 1974 Inventofls) Eugene Stephen Joseph It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below I v I Renumber claims 1, 2, 3, 4, 5, 6, 14, 15, 16, 17', 1s and 7 19 as claims 2-, "3, 4, '5, .6, 1, 15, 16, 17, l8, l9 and 14, respectively. a

Change the I dependencies of claim (formerly claim 1) ,Claim 7, claim 8, claim 9, claim 10 and claim 11 from "claim 6" to Change the dependencies of claim 3 (formerly claim 2) and claim 4 (formerly claim 3) from "claim 1" to -,claim 2 Change the dependency of claim 6 (formerly claim 5) from "claim 4" to claim 5 7 Change thedependency of clailim' lf'i (formerly claim l4)from "claim 13" to claim 14 I Change fhe dependency of claim 16 (formerly claim 15); from "claim '14" to claim 15 Change the dependency of claim 19 (formerly claim 18) from "claim 17" to claim 18 I Change the dependencies of claim 20, claim 21, claim 22 and claim 23 from "claim 19" to claim 14 y I v Signed/and sealed this 9th day of July-1 974.

(SEAL) Attest:

McCOY M. GIBSON, JR, I v I c MARSHA Ll; DANN Attesting Officer Commissioner of Patents 

1. Apparatus according to claim 6, wherein said at least one pair of members comprises at least two pairs of said members, the dimensions of the punch and die members of one of said pairs thereof being different from the dimensions of the punch and die members of the other of said pairs thereof, with the dimensions of the mounting means by which one of the punch and die members of one of said pairs thereof is removably mounted in the apparatus being the same as the dimensions of the mounting means by which one of the punch and die members of the other of said pairs thereof is removably mounted in the apparatus, and with the dimensions of the mounting means by which the other of the punch and die members of said one of said pairs thereof is removably mounted in the apparatus being the same as the dimensions of the mounting means by which the other of the punch and die members of said other of said pairs thereof is removably mounted in the apparatus.
 2. Apparatus according to claim 1, wherein the mounting means by which each of said punch and die members is removably mounted in the apparatus comprises a plurality of spaced mounting members, thE spacing between the mounting members by which said one of the punch and die members of said one of the pairs thereof is removably mounted in the apparatus being the same as the spacing between the mounting members by which said one of the punch and die members of said other of the pairs thereof is removably mounted in the apparatus, and the spacing between the mounting members by which said other of the punch and die members of said one of the pairs thereof is removably mounted in the apparatus being the same as the spacing between the mounting members by which said other of the punch and die members of said other of the pairs thereof is removably mounted in the apparatus.
 3. Apparatus according to claim 1, wherein each mounting means is substantially centrally disposed relative to the punch or die member which is removably mounted by said mounting means in the apparatus.
 4. Apparatus for performing fabricating operations on sheet material, the apparatus comprising at least two pairs of members, one of the members of each said pair thereof being a punch member and the other member of each said pair thereof being a die member with the punch and die members of each pair of said members being complementary, and the members of each said pair thereof being relatively movable towards and away from one another, so that said members, on said relative movement thereof towards one another, are brought into mating juxtaposed relationship for performing a fabricating operation or operations on sheet material disposed between said members, wherein the dimensions of the punch and die members of one of said pairs thereof are different from the dimensions of the punch and die members of the other of said pairs thereof, each of the punch and die members being removably mounted in the apparatus by mounting means which comprises a plurality of spaced mounting members, the dimensions of and spacing between the mounting members by which one of the punch and die members of one of the pairs thereof is removably mounted in the apparatus being the same as the dimensions of and spacing between the mounting members by which one of the punch and die members of the other of the pairs thereof is removably mounted in the apparatus, the dimensions of and spacing between the mounting members by which the other of the punch and die members of said one of the pairs thereof is removably mounted in the apparatus being the same as the dimensions of and spacing between the mounting members by which the other of the punch and die members of said other of the pairs thereof is removably mounted in the apparatus, and the spaced mounting members by which at least one of said punch and die members is removably mounted in the apparatus comprising a screw-threaded member which is engaged in said punch or die member and in the apparatus, and an anti-rotation locking pin which is spaced from the screw-threaded member and which is engaged in recesses provided in said punch or die member and in the apparatus.
 5. Apparatus according to claim 4, wherein said at least one of said punch and die members and the other member which is complementary thereto are formed for the forming of knock-outs in sheet material.
 6. Apparatus for performing fabricating operations on sheet material, the apparatus comprising at least one pair of members, one of the members of said pair thereof being a punch member and the other member of said thereof being a die member with the punch and die members of said pair of members being complementary, and with the members of said pair thereof being relatively movable towards and away from one another, so that said members, on said relative movement thereof towards one another, are brought into mating juxtaposed relationship for performing a fabricating operation or operations on sheet material disposed between said members, wherein each of said punch and die members is self-contained and is as a unit removably mounted in the apparatus by mounting means which is disposed wholly within the periphery oF said member as viewed in the direction in which said member and the other member which together with said member constitute said pair of members are relatively movable.
 7. Apparatus according to claim 6, wherein said at least one pair of members comprises at least two pairs of members, one of the members of each said pair thereof being a punch member and the other member of each said pair thereof being a die member with the punch and die members of each pair of said members being complementary, and with the members of each said pair thereof being relatively movable towards and away from one another, so that said members, on said relative movement thereof towards one another, are brought into mating juxtaposed relationship for performing a fabricating operation or operations on sheet material disposed between said members, wherein each of said punch and die members is self-contained and is a unit removably mounted in the apparatus by mounting means which is disposed wholly within the periphery of said member as viewed in the direction in which said member and the other member which together with said member constitutes one of said pairs of members are relatively movable.
 8. Apparatus according to claim 6, wherein the mounting means presented by at least one of the punch and die members of said pair thereof comprises a screw-threaded member which is engaged in said punch or die member and in the apparatus.
 9. Apparatus according to claim 6, wherein the mounting means presented by at least one of the punch and die members of said pair thereof comprises a single screw-threaded member which is engaged in said punch or die member and in the apparatus, a locating spigot in which the screw-threaded member is disposed being presented by said punch or die member and being in engagement within a complementary recess provided in the apparatus.
 10. Apparatus according to claim 6, further comprising at least one template, one of the punch and die members of said pair thereof being removably mounted on the template, and the template being removably mounted in the apparatus.
 11. Apparatus according to claim 6, further comprising at least one template removably mounted in the apparatus, the mounting means presented by at least one of the punch and die members of said pair thereof comprising a single screw-threaded member which is engaged in said punch or die member and in the template, and a locating spigot in which the screw-threaded member is disposed being presented by said punch or die member and being in engagement within a complementary recess provided in the template.
 12. Apparatus according to claim 10, wherein screw-threaded locating members are disposed through the template and engaged with the apparatus thereby to ensure accurate positioning of the template in the apparatus.
 13. Apparatus according to claim 10, wherein a clamping bar arrangement which is mounted in the apparatus is disposed in secure engagement with the template thereby to provide said removable mounting of the template in the apparatus.
 14. A combination according to claim 13, wherein said at least one pair of members comprises at least two pairs of said members, the dimensions of the punch and die members of one of said pairs thereof being different from the dimensions of the punch and die members of the other of said pairs thereof, the dimensions of the mounting means presented by one of the punch and die members of one of said pairs thereof being the same as the dimensions of the mounting means presented by one of the punch and die members of the other of said pairs thereof, and the dimensions of the mounting means presented by the other of the punch and die members of said one of pairs thereof being the same as the dimensions of the mounting means presented by the other of the punch and die members of said other of said pairs thereof.
 15. A combination according to claim 14, wherein the mounting means by which each of said punch and die members is removably mountable in the apparaTus comprises a plurality of spaced mounting members, the spacing between the mounting members presented by said one of the punch and die members of said one of the pairs thereof being the same as the spacing between the mounting members presented by said one of the punch and die members of said other of the pairs thereof, and the spacing between the mounting members presented by said other of the punch and die members of said one of the pairs thereof being the same as the spacing between the mounting members presented by said other of the punch and die members of said other of the pairs thereof.
 16. In combination, at least two pairs of members, one of the members of each said pair thereof being a punch member and the other member of each said pair thereof being a die member with the punch and die members of each said pair of said members being complementary, the dimensions of the punch and die members of one of said pairs thereof being different from the dimensions of the punch and die members of the other of said pairs thereof, each of said punch and die members presenting mounting means by which the member is removably mountable in apparatus for performing fabricating operations on sheet material, for relative movement of the punch and die members of each said pair thereof towards and away from one another, so that said punch and die members of each said pair thereof, on relative movement thereof towards one another, are brought into mating juxtaposed relationship for performing a fabricating operation or operations on sheet material disposed between said punch and die members, each mounting means being substantially centrally disposed relative to the punch or die member from which said mounting means is presented, the dimensions of the mounting means presented by one of the punch and die members of one of said pairs thereof being the same as the dimensions of the mounting means presented by one of the punch and die members of the other of said pairs thereof, and the dimensions of the mounting means presented by the other of the punch and die members of said one of said pairs thereof being the same as the dimensions of the mounting means presented by the other of the punch and die members of said other of said pairs thereof.
 17. In combination, at least two pairs of members, one of the members of each said pair thereof being a punch member and the other member of each said pair thereof being a die member with the punch and die members of each said pair of said members being complementary, the dimensions of the punch and die members of one of said pairs thereof being different from the dimensions of the punch and die members of the other of said pairs thereof, each of said punch and die members presenting mounting means by which the member is removably mountable in apparatus for performing fabricating operations on sheet material, for relative movement of the punch and die members of each said pair thereof towards and away from one another, so that said punch and die members of each said pair thereof, on relative movement thereof towards one another, are brought into mating juxtaposed relationship for performing a fabricating operation or operations on sheet material disposed between said punch and die members, the mounting means by which each of said punch and die members is removably mountable in the apparatus comprising a plurality of spaced mounting members, the dimensions of and spacing between the mounting members presented by one of the punch and die members of one of the pairs thereof being the same as the dimensions of and spacing between the mounting members presented by one of the punch and die members of the other of the pairs thereof, the dimensions of and spacing between the mounting members presented by the other of the punch and die members of said one of the pairs thereof being the same as the dimensions of and spacing between the mounting members presented by the other of the punch and die members of said other of the pairs thereof, and the spaced Mounting members by which at least one of said punch and die members is removably mountable in the apparatus comprising a screw-threaded member which is engageable in said punch or die member and in the apparatus, and an anti-rotation locking pin which is engageable in spaced relationship to the screw-threaded member in a recess provided in said punch or die member and in a recess in the apparatus.
 18. A combination according to claim 17, wherein said at least one of said punch and die members and the other member which is complementary thereto are formed for the forming of knock-outs in sheet material.
 19. In combination, at least one pair of members, one of the members of said pair thereof being a punch member and the other member of said pair thereof being a die member with the punch and die members of said pair of members being complementary, each of said punch and die members being self-contained and presenting mounting means by which said member is as a unit removably mountable in apparatus for performing fabricating operations on sheet material, for relative movement of the members of said pair thereof towards and away from one another, so that said members of said pair thereof, on relative movement thereof towards one another, are brought into mating juxtaposed relationship for performing a fabricating operation or operations on sheet material disposed between said members, the mounting means presented by each of said punch and die members being disposed wholly within the periphery of said member as viewed in the direction in which said member and the other member which together with said member constitutes said pair of members are relatively movable when removably mounted in the apparatus.
 20. A combination according to claim 19, wherein said at least one pair of members comprises at least two pairs of members, one of the members of each said pair thereof being a punch member and the other member of each said pair thereof being a die member with the punch and die members of each said pair of members being complementary, each of said punch and die members being self-contained and presenting mounting means by which said member is as a unit removably mountable in apparatus for performing fabricating operations on sheet material, for relative movement of the members of each said pair thereof towards and away from one another, so that said members of each said pair thereof, on relative movement thereof towards one another, are brought into mating juxtaposed relationship for performing a fabricating operation or operations on sheet material disposed between said members, the mounting means presented by each of said punch and die members being disposed wholly within the periphery of said member as viewed in the direction in which said member and the other member which together with said member constitutes one of said pairs of members are relatively movable when removably mounted in the apparatus.
 21. A combination according to claim 19, wherein the mounting means presented by at least one of the punch and die members of said pair thereof comprises a screw-threaded member which is engageable in said punch or die member and in the apparatus.
 22. A combination according to claim 19, wherein the mounting means presented by at least one of the punch and die members of said pair thereof comprises a screw-threaded member which is engageable in said punch or die member and in the apparatus, a locating spigot in which the screw-threaded member is disposable being presented by said punch or die member and being engageable within a complementary recess provided in the apparatus.
 23. A combination according to claim 19, wherein at least one of the punch and die members of said pair thereof incorporates a stripper arrangement constituted by a stiff but resiliently deformable plastics material.
 24. Apparatus for the forming of knock-outs in sheet material, the apparatus comprising at least two pairs of members, one of the members of each said pair thereof being a punch memBer and the other member of each said pair thereof being a die member with the punch and die members of each said pair of said members being complementary, and the members of each said pair thereof being relatively movable towards and away from one another, so that said members, on said relative movement thereof towards one another, are brought into mating juxtaposed relationship for the forming, by the complementary punch and die members, of knock-outs in a sheet of formable material disposed between said members, wherein the dimensions of the punch and die members of one of said pairs thereof differ from the dimensions of the punch and die members of the other of said pairs thereof, each of said punch and die members being self-contained and being as a unit removably mounted in the apparatus by a plurality of spaced mounting members which comprise a screw-threaded member engaged in said punch or die member and in a template removably mounted in the apparatus, and an anti-rotation locking pin which is spaced from the screw-threaded member and which is engaged in recesses provided in said punch or die member and in the template, a locating spigot in which the screw-threaded member is disposed being presented by said punch or die member and being in engagement within a complementary locating recess provided in the template, the spaced mounting members presented by each of said punch and die members being disposed wholly within the periphery of said punch or die member as viewed in the direction in which said punch or die member and the other member which together with said punch or die member constitutes one of said pairs of members are relatively movable, and the dimensions of and spacing between the mounting members by which said punch and die members are removably mounted in the apparatus being substantially equal. 